Variable Functions - Global Variables - Static Variables

Variable Functions

• is_array() :- Finds whether a variable is an array
  - Description:-is_array( var) :-Returns TRUEif varis an array, FALSEotherwise.
• is_float() :- Finds whether a variable is a float
  - Description;-is_float(var) Returns TRUEif varis a float, FALSEotherwise.
• is_int() :- Find whether a variable is an integer
  - Description:-is_int(var) Returns TRUEif varis an integer FALSEotherwise.
• is_string() :- Finds whether a variable is a string
  - Description:-is_string(var) Returns TRUEif varis a string, FALSEotherwise.
• is_object() :- Finds whether a variable is an object
  - Description:-is_object(var) Returns TRUEif varis an object, FALSEotherwise.
• is_bool() :- Finds out whether a variable is a boolean
  - Description:-is_bool(var) Returns TRUEif the varparameter is boolean.
• is_null :- Finds whether a variable is NULL
  - Description :- is_null(var) Returns TRUEif varis null , FALSEotherwise See the null type when a variable is considered to be NULLand when not.

---

Global Variables

• A global variable can be accessed in any part of the program.
• However, in order to be modified, a global variable must be explicitly declared to be global in the function in which it is to be modified.
• This is accomplished, conveniently enough, by placing the keyword GLOBAL in front of the variable that should be recognized as global.
• Placing this keyword in front of an already existing variable tells PHP to use the variable having that name.

Consider an example:

<?php
$somevar=15;
functionaddit()
{
GLOBAL$somevar;
$somevar++;
print"Somevar is $somevar";
}
function addit1()
{
GLOBAL $somevar;
$somevar++;
print "Somevar is $somevar";
}
addit();
addit1();
?>

Output:-

Some var is 16
Some var is 16

---

Static variables

• A static variable retains its value between calls to a function but is visible only within that function.
• You can declare a variable static with the static keyword.

For example :  function update_counter

<?php
function update_counter ( )
{
static $counter = 0;
$counter++;
echo "Static counter is now $counter";
}
$counter = 10;
update_counter( );
update_counter( );
echo “counter is $counter";
?>

Output:-

Static counter is now 1 Static counter is now 2 Global counter is 10